HVAC systems can comprise an indoor heat exchanger, an outdoor heat exchanger, a compressor, an expansion device, and other components. Some HVAC systems may comprise a reversing valve, enabling the system to function both as a heat pump and as an air conditioner. During heating modes the indoor heat exchanger functions as a condenser and the outdoor heat exchanger functions as an evaporator. During cooling modes the roles of the heat exchangers are reversed. The indoor and outdoor heat exchangers are typically the same size, but not always. Different sized heat exchangers may be due to space constraints, material differences, or other reasons. The volume ratio of indoor to outdoor coils may lead to charge imbalances, leading to high pressure and other problems.